Faculty Opinions recommendation of Three-dimensional structure of herpes simplex virus from cryo-electron tomography.

ABSTRACT Human nectin1 (hNectin1), an adhesion molecule belonging to the nectin family of the immunoglobulin superfamily, mediates entry of herpes simplex virus (HSV) into cells. The hNectin1 domain that mediates virus entry into cells and also binds glycoprotein D (gD) has been localized to the first N-terminal V-type domain. The poliovirus receptor (PVR) is a structural homolog to nectins, but it cannot function as an HSV entry receptor. hNectin1-PVR chimeras were constructed to functionally locate the site on hNectin1 involved in HSV entry (HSV entry site). The epitope recognized by monoclonal antibody (MAb) R1.302, which is able to block HSV entry, was also located. The chimeric receptors were designed to preserve the overall structure of the V domain. The HSV entry activity mapped entirely to the hNectin1 portion located between residues 64 and 94 (64-94), likely to encode the C, C′, and C" β-strands and intervening loops. In turn, this site consisted of two portions: one with low-level basal activity for HSV entry (77-94), and one immediately upstream (residues 64 to 76) which greatly enhanced the HSV entry activity of the downstream region. The gD-binding site mapped substantially to the same site, whereas the MAb R1.302 epitope also required a further downstream portion (95-102). The involvement of the 64-76 portion is at difference with previous indirect mapping results that were based on competitive binding studies (C. Krummenacher et al., J. Virol. 74:10863–10872, 2000). The A, A′, B, D, E, F, and G β-strands and intervening loops did not appear to play any role in HSV entry. According to the predicted three-dimensional structure of PVR, the C C′ C" site is located peripherally in the V domain and very likely represents an accessible portion at the cell surface.

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Visualization of Tegument-Capsid Interactions and DNA in Intact Herpes Simplex Virus Type 1 Virions

Journal of Virology ◽

10.1128/jvi.73.4.3210-3218.1999 ◽

1999 ◽

Vol 73 (4) ◽

pp. 3210-3218 ◽

Cited By ~ 186

Author(s):

Z. Hong Zhou ◽

Dong Hua Chen ◽

Joanita Jakana ◽

Frazer J. Rixon ◽

Wah Chiu

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Virus Type ◽

Herpes Simplex Virus Type ◽

Three Dimensional ◽

Dimensional Structure ◽

Cellular Transport ◽

Capsid Shell ◽

Simplex Virus

ABSTRACT Herpes simplex virus type 1 virions were examined by electron cryomicroscopy, allowing the three-dimensional structure of the infectious particle to be visualized for the first time. The capsid shell is identical to that of B-capsids purified from the host cell nucleus, with the exception of the penton channel, which is closed. The double-stranded DNA genome is organized as regularly spaced (∼26 Å) concentric layers inside the capsid. This pattern suggests a spool model for DNA packaging, similar to that for some bacteriophages. The bulk of the tegument is not icosahedrally ordered. However, a small portion appears as filamentous structures around the pentons, interacting extensively with the capsid. Their locations and interactions suggest possible roles for the tegument proteins in regulating DNA transport through the penton channel and binding to cellular transport proteins during viral infection.

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Cryo-Electron Tomography of the Herpesvirus Procapsid Reveals Interactions of the Portal with the Scaffold and a Shift on Maturation

mBio ◽

10.1128/mbio.03575-20 ◽

2021 ◽

Vol 12 (2) ◽

Author(s):

Michael H. C. Buch ◽

William W. Newcomb ◽

Dennis C. Winkler ◽

Alasdair C. Steven ◽

J. Bernard Heymann

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Electron Tomography ◽

Dna Packaging ◽

Herpes Simplex Virus 1 ◽

Portal Protein ◽

Capsid Shell ◽

Cryo Electron Tomography ◽

Simplex Virus ◽

Hsv 1

ABSTRACT Herpes simplex virus 1 (HSV-1) requires seven proteins to package its genome through a vertex in its capsid, one of which is the portal protein, pUL6. The portal protein is also thought to facilitate assembly of the procapsid. While the portal has been visualized in mature capsids, we aimed to elucidate its role in the assembly and maturation of procapsids using cryo-electron tomography (cryoET). We identified the portal vertex in individual procapsids, calculated a subtomogram average, and compared that with the portal vertex in empty mature capsids (A-capsids). The resulting maps show the portal on the interior surface with its narrower end facing outwards, while maintaining close contact with the capsid shell. In the procapsid, the portal is embedded in the underlying scaffold, suggesting that assembly involves a portal-scaffold complex. During maturation, the capsid shell angularizes with a corresponding outward movement of the vertices. We found that in A-capsids, the portal translocates outward further than the adjacent capsomers and strengthens its contacts with the capsid shell. Our methodology also allowed us to determine the number of portal vertices in each capsid, with most having one per capsid, but some none or two, and rarely three. The predominance of a single portal per capsid supports facilitation of the assembly of the procapsid. IMPORTANCE Herpes simplex virus 1 (HSV-1) infects a majority of humans, causing mostly mild disease but in some cases progressing toward life-threatening encephalitis. Understanding the life cycle of the virus is important to devise countermeasures. Production of the virion starts with the assembly of an icosahedral procapsid, which includes DNA packaging proteins at a vertex, one of which is the dodecameric portal protein. The procapsid then undergoes maturation and DNA packaging through the portal, driven by a terminase complex. We used cryo-electron tomography to visualize the portal in procapsids and compare them to mature empty capsids. We found the portal located inside one vertex interacting with the scaffold protein in the procapsid. On maturation, the scaffold is cleaved and dissociates, the capsid angularizes, and the portal moves outward, interacting closely with the capsid shell. These transformations may provide a basis for the development of drugs to prevent HSV-1 infections.

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Three-dimensional structure of the radial spokes reveals heterogeneity and interactions with dyneins in Chlamydomonas flagella

Molecular Biology of the Cell ◽

10.1091/mbc.e11-08-0692 ◽

2012 ◽

Vol 23 (1) ◽

pp. 111-120 ◽

Cited By ~ 50

Author(s):

Cynthia F. Barber ◽

Thomas Heuser ◽

Blanca I. Carbajal-González ◽

Vladimir V. Botchkarev ◽

Daniela Nicastro

Keyword(s):

Electron Tomography ◽

Three Dimensional ◽

Dimensional Structure ◽

Flagellar Motility ◽

Three Dimensional Structure ◽

Radial Spoke ◽

Cryo Electron Tomography ◽

Radial Spokes ◽

Axonemal Dynein ◽

Subtomogram Averaging

Radial spokes (RSs) play an essential role in the regulation of axonemal dynein activity and thus of ciliary and flagellar motility. However, few details are known about the complexes involved. Using cryo–electron tomography and subtomogram averaging, we visualized the three-dimensional structure of the radial spokes in Chlamydomonas flagella in unprecedented detail. Unlike many other species, Chlamydomonas has only two spokes per axonemal repeat, RS1 and RS2. Our data revealed previously uncharacterized features, including two-pronged spoke bases that facilitate docking to the doublet microtubules, and that inner dyneins connect directly to the spokes. Structures of wild type and the headless spoke mutant pf17 were compared to define the morphology and boundaries of the head, including a direct RS1-to-RS2 interaction. Although the overall structures of the spokes are very similar, we also observed some differences, corroborating recent findings about heterogeneity in the docking of RS1 and RS2. In place of a third radial spoke we found an uncharacterized, shorter electron density named “radial spoke 3 stand-in,” which structurally bears no resemblance to RS1 and RS2 and is unaltered in the pf17 mutant. These findings demonstrate that radial spokes are heterogeneous in structure and may play functionally distinct roles in axoneme regulation.

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The Pattern of Tegument-Capsid Interaction in the Herpes Simplex Virus Type 1 Virion Is Not Influenced by the Small Hexon-Associated Protein VP26

Journal of Virology ◽

10.1128/jvi.75.23.11863-11867.2001 ◽

2001 ◽

Vol 75 (23) ◽

pp. 11863-11867 ◽

Cited By ~ 27

Author(s):

Dong-Hua Chen ◽

Joanita Jakana ◽

David McNab ◽

Joyce Mitchell ◽

Z. Hong Zhou ◽

...

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Virus Type ◽

Herpes Simplex Virus Type ◽

Three Dimensional ◽

Dimensional Structure ◽

Binding Properties ◽

Potential Binding ◽

Simplex Virus

ABSTRACT Examination of the three-dimensional structure of intact herpes simplex virus type 1 (HSV-1) virions had revealed that the icosahedrally symmetrical interaction between the tegument and capsid involves the pentons but not the hexons (Z. H. Zhou, D. H. Chen, J. Jakana, F. J. Rixon, and W. Chiu, J. Virol. 73:3210–3218, 1999). To account for this, we postulated that the presence of the small capsid protein, VP26, on top of the hexons was masking potential binding sites and preventing tegument attachment. We have now tested this hypothesis by determining the structure of virions lacking VP26. Apart from the obvious absence of VP26 from the capsids, the structures of the VP26 minus and wild-type virions were essentially identical. Notably, they showed the same tegument attachment patterns, thereby demonstrating that VP26 is not responsible for the divergent tegument binding properties of pentons and hexons.

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